I just finished replacing my headgasket on my car. I bought a head from the junk yard and got it rebuilt. (Replaced valve seals and so on). After I finished putting the car back together, it was running perfect. One day I left it to idle while I was washing my hands. I just herd a clank sound and the car shut off. After trying to start it back up, it would crank and then stop at a certain point. Then we tried turning the crank and found out that the engine was jammed. There was still full oil in the engine. I don't know what to do. I am thinking weather I should buy a low mileage JDM motor. Or trying to rebuild this one. What do you guys think the best thing to do. I didn't pull apart the engine yet to figure out what is wrong with it. I am only 17 and it took me forever to get the funds to rebuild the engine. Now I am only $75 away from getting the rest of cash for the JDM Engine. Here is a list of what I did while I replaced the head. HKS 1.2mm headgasket, ARP Head bolts, 6 NGK Platinum Spark Plugs(Know they aren't the best for the 7MGTE), MSD Spark Plug Wires, replaced all seals, timing belt, all drive belts, oil, antifreeze, lower radiator hose, oil cooler lines and a few other little things. I know even if I buy a JDM motor, I am going to use back all of these parts. But it just hurt so bad that after I rebuilt the engine then this decides to happen. If I had known from the beginning, I would have just bought the JDM engine to begin with. Any advice would do. Thanks.